Ananthakrishnan 2014.

Methods	Retrospective population based cohort study
Participants	6823 patients were followed 2754 patients had undergone colonoscopy within the last 36 months and 4059 patients had not undergone colonoscopy within the last 36 months
Interventions	Colonoscopic surveillance within 36 months versus no colonoscopic surveillance within 36 months
Outcomes	Primary outcome: Diagnosis of CRC determined by diagnosis codes for colon or rectal cancer
Notes	Attempts to control for bias: 1. Satistical analysis: (a) The Mann‐Whitney test was used for non‐parametric comparisons (b) Examined the association between colonoscopy and risk of CRC by stratifying the cohort according to sex, type of IBD, and a diagnosis of PSC 2. The characteristics between the recent surveillance and non‐recent surveillance groups were compared. Patients with a recent colonoscopy were more likely to be younger, had a slightly longer duration of follow‐up evaluation, and were less likely to be women or have a diagnosis of UC. There was no difference in racial distribution between the two groups